The invention relates to a coupling element for optical coupling of at least one optoelectronic transducer to at least one optical wave guide. Coupling elements such as these are particularly suitable for coupling transmitting and receiving elements, which are disposed closely adjacent to one another, to optical wave guides via closely adjacent optical channels. The coupling element has an image plate with a large number of small-diameter optical wave guides.
It is known for coupling elements to be used for coupling an optical wave guide to an optoelectronic transducer, for example a receiving diode or a VCSEL laser. The coupling elements form an optical interface between the optoelectronic transducers and the optical wave guides. Normally, this interface is formed by a plug-in system of plug connectors, with the optical coupling being provided by lenses or wave guide stubs. In some cases, adjustment of the individual components is complex, and hence costly.
The publication titled xe2x80x9cThe PONI-1 Parallel-Optical Linkxe2x80x9d, Proc. 49th ECTC 1999, pages 763-769 discloses a mounting block, on which a number of optoelectronic transducers are mounted. The mounting block has a pair of guide pins, which provide guidance for an optical connector that is to be coupled. The optical coupling between the optoelectronic transducers and the wave guides in the connector is provided by an image plate having a large number of optical microwave guides, with the image plate being disposed above the optoelectronic transducers.
The optical microwave guides are in the form of thin glass fibers, which provide optical channels with a diameter of, for example, 10 micrometers. The image plate allows optical signals to be transmitted from its input to its output essentially without any divergence. The image plate thus transmits the light between an array of optoelectronic transducers and a corresponding array of optical wave guides, while maintaining the respective pattern. This makes it possible to save an adjustment step, since the image plate does not need to be finely adjusted with respect to the optoelectronic transducers and the optical wave guides to be coupled. All that is required is to position the optical wave guides and the optical wave guide connectors accurately with respect to the optoelectronic transducers.
A further advantage of the use of an image plate is that it protects the optoelectronic transducers against direct contact with the optical wave guides to be coupled and an optical wave guide connector.
The known configuration using an image plate has the disadvantage however, that the optical connectors to be coupled are positioned with respect to the mounting block via the guide pins on the mounting block. It is thus necessary to provide mounting blocks with different configurations of guide pin configurations for different connectors and optical wave guide systems to be coupled, that is to say the mounting blocks must be configured differently.
It is accordingly an object of the invention to provide a coupling element that overcomes the above-mentioned disadvantages of the prior art devices of this general type, which provides optical coupling in a simple and effective manner between the elements, and with the aim of avoiding any restriction with regard to the mount which can be used for the mounting of the optoelectronic transducers.
With the foregoing and other objects in view there is provided, in accordance with the invention, a coupling element for optical coupling at least one optoelectronic transducer to at least one optical wave guide. The coupling element contains a guide element and an image plate with a large number of small-diameter optical wave guides. The image plate is connected to the guide element and couples the at least one optical wave guide.
The solution according to the invention is accordingly distinguished by the fact that the image plate is connected to the guide element for coupling the at least one optical wave guide. According to the invention, the guide element is thus not attached to the mounting block with the optoelectronic transducers, but are attached to the image plate itself. This allows any desired mount to be used for mounting and making electrical contact with the optoelectronic transducers. All that is required is to connect the combination of the image plate and the guide element to the optical conductors to be coupled, and then to fix and adjust the configuration with respect to the optoelectronic transducers.
There are a large number of options for connecting the guide element to the image plate, which may be carried out directly or indirectly via intermediate elements. For example, the guide element can be firmly connected to the image plate, in particular being bonded or soldered to it. Furthermore, it is possible to provide for the image plate to have holding elements for attaching the guide elements. The holding elements are, for example, longitudinal grooves on the image plate.
It is likewise within the scope of the invention for the image plate and the guide device to be connected by a frame that at least partially surrounds them. Alternatively, the image plate is embedded in a holding plate, and the guide element is likewise attached to the holding plate.
The image plate and the guide element are advantageously elastically connected to one another. For this purpose, the invention provides, for example, for the above-mentioned frame to have a sprung configuration for a holding plate that connects the image plate and the guide elements to one another to have elastic characteristics. The elastic connection of the image plate and guide element also ensures, in the case of manufacturing tolerances, that an optical wave guide or connector to be coupled can be reliably coupled to the guide device.
One preferred embodiment to the invention relates to the coupling of the optical wave guides that are disposed in at least one optical connector to be coupled. The guide element is in this case used for coupling the optical connector. For this purpose, they are, in particular, in the form of pins or holding openings for holding and guiding the optical connector. By way of example, they form a circular or rectangular holding opening for an optical wave guide connector.
It is likewise within the scope of the invention, however, for the optical wave guide to be disposed on or in a mount, for example on a printed circuit board and/or in a wave guide plane, and to be coupled at the end to the optoelectronic transducers, without using optical connectors. In this case, the guide element preferably is guided in the mount. In particular, the guide element preferably engages in grooves in the wave guide plane, in which a number of optical wave guides are disposed, in order to fix and couple the wave guides.
In a further preferred refinement to the invention, the image plate and the at least one optoelectronic transducer are at least partially jointly encased by an optically transparent encapsulation compound. This results in the optoelectronic transducers and the image plate are encapsulated from the environment, and are protected against moisture, dirt, etc. In particular, this ensures that the optical path between the optoelectronic transducers and the image plate runs in a protected manner within the encapsulation compound.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a coupling element, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.